Say what you like about the Queen, but her pulling power is undimmed. Around 7,000 workers took to the streets in London to celebrate May day; on the same day in Exeter, 180 miles away, 20,000 people turned out to welcome the Queen as she began her golden jubilee tour, marking the 50th anniversary of her accession to the throne.

The celebrations have presented royal memorabilia producers with a golden opportunity to profit from collectors' appetite for commemorative plates, cups, mugs, tankards and other trinkets.

A limited edition Spode plate priced at £135 and a mug costing £35 which were made exclusively for the John Lewis Partnership have already sold out.

If you are struck on Her Majesty, the department store group is also selling the official range of commemorative souvenirs commissioned by the Royal Collection. This includes a golden jubilee goblet, crystal glasses, tankards, silver coasters and Caithness glass paperweights.

Steven Jackson, a retired local government officer and secretary of the Commemorative Collectors Society, has built up a sizeable collection of royal and regal memorabilia.

This includes 1953 limited edition coronation plates bought for around £50 and a Coalport china vase with rams' head handles produced to mark the Queen's silver jubilee and costing around £70.

In 1994, he spent £60 adding a plate to mark the Queen's first state visit to Russia, followed by a 1995 plate marking her visit to democratic South Africa under president Nelson Mandela.

"For most ordinary collectors these are not logical purchases for profit, for me it is their historical significance. They are memory platters which reflect public taste and attitudes of the time," he says.

Although limited edition commemorative china is typically hand-painted and made to a very high standard of craftsmanship, anyone driven to buy such mementoes for investment motives should be aware that it takes generations before they may turn a profit.

Oddly enough, the lower-priced jubilee items may be a better bet than the higher priced, better made collector's pieces.

"However, very few of the several thousand mass-produced mugs will have lasted for that length of time. All but a handful of these mugs would have been damaged, as they are put to everyday use in staff canteens, kitchens or in bathrooms to hold toothbrushes. So, after 20 years the few remaining cheap mugs that are still in perfect condition fetch up to £20 or £25, giving a much higher return on an initial investment of probably £2."

Back in 1953, to mark the Queen's coronation, many potteries were commissioned by local councils to produce a coronation mug made to an official design and which was given away to schoolchildren in their area. Those coronation mugs which have survived intact are now fetching up to £20.

Chris Haines, who runs online memorabilia mart www.royalcoll.fsnet.co.uk says: "The Doulton tankard, which went on sale in 1953, is a good example of how a some commemorative items, through a twist of fate, can become very collectable.

"At the time when it was made no one could have guessed that it would be the last ever memento to come out of the famous Doulton pottery at Lambeth. The Tankard, which was signed by Agnete Hoy, the head of design at the time, would have sold for about £15 then and is now valued at £140."

If you see a Prince Charles "big ears" mug, snap it up. "Visit car boot sales and local fairs to seek out a Prince Charles mug designed by cartoonist Marc Boxer, with an ear as the handle. The mug is one of the few cheapie Royal souvenirs that now fetch high prices. Sold in 1981 for around £1, one in good nick will now fetch £50," says Mr Haines.

One of the most collectable royal commemorative plates was produced in 1972 to mark the death of the Duke of Windsor, the former king. A very limited edition which used a contemporary photo of the exiled duke and priced at around £35, it is currently selling for more than £150 provided it is in good condition.

If you decide to buy royal memorabilia for investment purposes, be aware that it is a mass market where few people make any money except the producers. It's also hardly new; 300 years ago, glass makers were selling engraved goblets to mark the accession of Queen Anne in 1702. They cost a shilling to make but were offloaded for a guinea a time.

If you would like more information about this subject, contact The Commemorative Collectors Society, which represents the interests of royal and regal memorabilia collectors.

It organises meetings and exhibitions and publishes regular reviews of commemoratives. Membership details are available from The Secretary, The Commemorative Collectors Society, The Gardens, Gainsborough Road, Winthorpe near Newark, Nottinghamshire NG24 2NR.